|Year : 2015 | Volume
| Issue : 2 | Page : 97-102
Device-associated infection rates and median length of acquiring device-associated infection in an intensive therapeutic unit of an Indian hospital
Angshuman Jana, NK Pal, Arijit Majumdar, Jayeeta Mitra, Anirban Jana, Soumali Biswas, Babita Bag
Department of Pathology and Microbiology, IPGME and R, Kolkata, West Bengal, India
|Date of Web Publication||5-Aug-2015|
Haldia, Purba Medinipore, 721605, West Bengal
Source of Support: None, Conflict of Interest: None
Background: Hospital acquired infection (HAIs) nowadays is one of the leading causes of mortality in the ITU. Limited data is available regarding burden of HAIs specially device associated infections (DAIs) in Indian ITU. This study was aimed at determining the occurrence of DAIs including magnitude of device associated infections per 100 hospital admission, magnitude of device associated infection cases per 1000 bed days, incidence of infections per 1000 device days, median time for detection of DAIs, prevalent organisms and their antibiogram. Patients included in this study were taken from a 25 bedded intensive therapeutic unit (ITU), in a hospital in India.
Methods: A prospective surveillance was performed over two years duration from July 2011 to June 2013. 578 patients were followed until discharge who admitted to this ITU and stay for more than 48 hours. HAIs were identified according to the CDC/NNIS definition. Data were analyzed with descriptive statistics.
Results: The incidence rate for DAIs was 19.55%(113/578). More than 50% were associated with different comorbid illness mainly malignancy (47%). The device utilization was very high in case of urinary catheter (0.838) and IV catheter (0.742) but the incidence density was maximum in case of ventilator associated pneumonia (VAP = 13.89%). Median time of acquiring VAP, CAUTI, CRBSI were maximum in between (9 to 14 days), (16 to 21 days) and (12 to 17) days respectively demands need for regular follow up of this devices within that periods. Major pathogens for VAP were Klebsiella (28.95%), Acinetobacter (26.3%); CA-UTI mostly caused by E. coli (18.2%). CRBSI mainly caused by MRSA (25.9%), Acinetobacter (18.5%).
Conclusion: A high rate of device associated infections, particularly VAP, were observed in this study. One of the main strategy to prevent nosocomial infections in the ITU is early change of invasive devices based on its median time of infection and to avoid its unnecessary prolong use.
Keywords: Device-associated infection, intensive therapeutic unit and multidrug resistance, median time of infections
|How to cite this article:|
Jana A, Pal N K, Majumdar A, Mitra J, Jana A, Biswas S, Bag B. Device-associated infection rates and median length of acquiring device-associated infection in an intensive therapeutic unit of an Indian hospital. J Med Trop 2015;17:97-102
|How to cite this URL:|
Jana A, Pal N K, Majumdar A, Mitra J, Jana A, Biswas S, Bag B. Device-associated infection rates and median length of acquiring device-associated infection in an intensive therapeutic unit of an Indian hospital. J Med Trop [serial online] 2015 [cited 2022 Oct 4];17:97-102. Available from: https://www.jmedtropics.org/text.asp?2015/17/2/97/161509
| Introduction|| |
In intensive therapeutic unit (ITU), various invasive devices have been used indiscriminately for long durations. Hospital acquired infection, unfortunately, is an important and critical issue related to high morbidity and mortality in admitted patients particularly in high-risk groups in ITU. Nowadays, devices are the most important causes of Hospital-acquired infections due to their prolonged use and lack of regular care or timely change when required, particularly in ITU. , Various factors contribute to this malady particularly prolonged length of hospital stay, excessive use of invasive devices for prolonged periods (device utilization [DU]), indiscriminate use of antibiotics, and increased bacterial resistance.  This study was conducted in order to investigate the epidemiological characteristics of device-associated infections (DAIs) in reference to total infection rate and DAI rate, DU ratio, infections incidence density, median time of its detection, and pathogens most commonly associated with infection and their antibiogram pattern in an Indian ITU.
| Methods|| |
A prospective cohort study was conducted from July 2011 to June 2013 in a 25 bedded ITU of a government teaching hospital in Kolkata, India. Samples were collected regularly and sent to the microbiological laboratory for in vitro susceptibility testing of clinical isolates using standardized methods, as described in the Centers for Disease Control and Prevention/National Healthcare Safety Network (CDC/NHSN) definitions.  On an average, in this ITU, the nurse-to-patient ratio was 1:2 and physician-to-patient ratios was 1:4. The average ITU cleaner-to-bed ratio was 1:8. Before the present study, no surveillance was performed in this ITU.
The information on nosocomial infection was collected prospectively by the researcher and an infection control practitioner of the study hospital. The researcher designed a specific form to gather the information on nosocomial infections; number of infection, infection site, occurrence date, pathogens, and drug susceptibility. All charts and related records including laboratory data, medical and nursing records, were examined and recorded on a specific form by the researcher. Hospital-acquired (nosocomial) infections were defined in accordance with the National Nosocomial Infection Surveillance definition of CDC. 
This study had gotten specific approval from the Ethical Committee of the institute.
The total study population over the last 2 years was 578 who had an ITU stay of more than 48 h. A total of 37 patients died (5 - malignancy, 8 - cerebrovascular accident [CVA] with ventilator-associated pneumonia [VAP], 4 - hepatic failure, 3 - chronic renal failure, 3 - chronic obstructive pulmonary disease [COPD], 5 - ischemic heart disease, 1 - snake bite, 2 - puerperal sepsis, 7 - septicemia, 4 - meningitis and encephalitis) during this period were also included. DAIs rate, incidence density of VAP (number of cases per 1,000 mechanical ventilator days), catheter-related bloodstream infection (CR-BSI) (number of cases per 1,000 IV catheter days), catheter-associated urinary tract infection (CAUTI) (number of cases per 1,000 urinary catheter [UC] days), device-associated healthcare-associated infection (HAI) per 1,000 patient days, DU ratio were recorded based on the CDC/NHSN definitions  and to calculate the median time of acquiring DAIs, that is the median few values when the DAIs were commonly detected. DU ratio calculation: DU ratios were calculated by dividing the total number of device-days by the total number of patient-days. Device-days are the total number of days of exposure to the device (catheter line, mechanical ventilation [MV], or UC) for all patients in the selected population during the specified period. Patient-days are the total number of days that patients are in the ITU during the specified period. ,
Sampling and Culture Technique
Ventilator associated pneumonia
Tracheal aspirate from the endotracheal tube was cultured aerobically and stained with Gram stain.
Catheter related bloodstream infection
Intravenous catheters were removed aseptically, and the distal 5 cm was amputated and cultured using a standardized semi-quantitative method. Concomitant blood cultures were drawn percutaneous in all cases. 
Catheter-associated urinary tract infection
A urine sample was aseptically aspirated from the sampling port of UC and cultured quantitatively. In all cases, standard laboratory methods were used to identify micro-organisms, and a standardized susceptibility test was performed. 
Ventilator-associated pneumonia is indicated in a mechanically ventilated patient with a chest radiograph that shows new or progressive infiltrates, consolidation, cavitation, or pleural effusion. The patient must also have at least 1 of the following criteria: New onset of purulent sputum or change in character of sputum; organism cultured from blood; or isolation of an etiologic agent from a specimen obtained by tracheal aspirate, bronchial brushing or bronchoal veolar lavage, or biopsy.
Catheter related bloodstream infection
Catheter-related bloodstream infection is laboratory-confirmed infection where a patient with an intravenous catheter has a recognized pathogen that is isolated from 1 or more percutaneous blood cultures after 48 h of vascular catheterization and is not related to an infection at another site. The patient also has at least 1 of the following signs or symptoms: Fever (temperature >38°C), chills, or hypotension. In the case of skin commensals (for example, diphtheroids, Bacillus spp., coagulase-negative staphylococci, or micrococci), the organism is cultured from 2 or more blood cultures.
Catheter-associated urinary tract infection
For the diagnosis of CAUTI (the patient must meet 1 of the 2 criteria. The first criterion is when a patient with a UC has 1 or more of the following symptoms with no other recognized cause: Fever (temperature >38°C), urgency, or suprapubic tenderness when the urine culture is positive for 105 colony-forming unit sperm lormore, with no more than 2 microorganisms isolated. The second criterion is when a patient with a UC has at least 2 of the following criteria with no other recognized cause: Positive dipstick analysis for leukocyte esteraseor nitrate, pyuria (≥10 leukocyte sperm of urine), organisms see non-Gram stain, clinical diagnosis of urinary tract infection (UTI), or physician initiates appropriate therapy for a UTI.
Statistical analyses were performed using descriptive statistics such as frequency and percentages and the median value. Data analysis was done using Microsoft Excel 2010.
| Results|| |
Characteristics of Study Subjects
In this study, sex did not much correlate with the occurrence of DAIs but increasing age the incidence increases. In our study population, most were in the age group of 40-60 years (37.4%), however, HAIs occurred most often in the age group of >60 years (32.7%) compared to the age group of 40-60 years (20.6%) and it was much less in 20-40 years (18.9%). Many of the DAIs were also associated with different co-morbid illnesses viz. malignancy (47%), chronic renal disease (CRD) (42.8%), diabetes (35.2%), COPD (30.5%), chronic liver failure (27%), and CVA cases (15.6%) [Table 1].
Incidence of Nosocomial Infection
This study diagnosed DAIs based on the clinical and culture-proven evidence according to the CDC definition, and the incidence was 19.55% (113/578). More than 90% of them were associated with at least one of the invasive devices.
Ventilator Associated Pneumonia
The overall rate of VAP in the ITU was 6.37%, and incidence density was 19.47/1,000 MV days. The DU ratio was 0.305. CAUTI: The overall rate of CAUTI in the ICU was 5.54%, and incidence density was 3.81/1,000 catheter days. The DU ratio was 0.836. CR-BSI: The overall rate of CR-BSI in the ICU was 4.53%, and incidence density was 3.77/1,000 catheter days. The DU ratio was 0.737 [Table 2].
|Table 2: Incidence densities of device-associated infections rate, device utilization ratio, DAI/1,000 patient days or 1,000 device days|
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Median Time from Admission to Development of Nosocomial Infection
In this study, median time of acquiring VAP, CAUTI, CR-BSI were 9-14 days, 16-21 days, and 12-17 days [Figure 1], respectively, from the time of admission. Whereas the median time of pneumonia, UTI and BSI were 24-39, 41, and 39, respectively, where no such invasive devices were used. Since the time of acquiring nosocomial infections are much shorter in case of use of invasive devices we should change the devices within that specified period to avoid the development of DAI [Table 3].
Distribution of Pathogens by Major Infection Sites
In the present study, most commonly found pathogens in ITU were Klebsiella spp. (23.9%), Acinetobacter spp. (22.12%) Pseudomonas spp. (19.45%) Staphylococcus aureus (17.7%) followed by Escherichia coli (15%). Most frequent DAI was VAP (6.37%) and most prevalent organisms in this group were mostly Gram-negative ones like Klebsiella spp.(30.6%), Acinetobacter spp.(26.5%), Pseudomonas spp.(22.4%) and methicillin-resistant S. aureus (10.2%). CAUTI was the second most common HAIs and the main causative organisms also were Gram-negative bacteria of Enterobacteriacae group, of which E. coli and Pseudomonus spp. (19.4%) each, Klebsiella spp. (16.6%), S. aureus and Candida spp. (11%) each was common. Among CR-BSI, Gram-negative and Gram-positive organisms were equally found. Among Gram-positive organisms S. aureus (24.2%), coagulase-negative Staphylococcus (CONS) (10.7%) and Enterococcus and among Gram-negative organisms Acinetobacter spp. (21.4%), E. coli (14.3%), Klebsiella spp. (10.7%) were commonly found [Table 4].
Use of Antibiotics, Overall Bacterial Profile and Resistance
About 68% of the organisms were β lactamase producers, 60-90% of them showing multidrug resistance against 2 nd and 3 rd generation cephalosporins, 90-100% against piperacillin and 93-100% against aztreonam, 34-60% against cefepime, 54-77% against amoxicillin-clavulanic acid. Multidrug resistance to both extended spectrum beta-lactamase (ESBL) and AmpC producers were found to be resistant to amikacin (32-44%), ciprofloxacin (67-89%), and cotrimoxazole (82-83%), respectively. Imipenem showing only 6% resistance in this study considered nowadays as the frontline antibiotic for the treatment of nosocomial infections caused by Enterobacteriaceae producing ESBL and AmpC beta-lactamases [Table 5].
| Discussion|| |
Utilization of invasive devices is increasing in the ITU setting to provide long-term access, but infection remains a major problem. Early diagnosis and treatment are vital to reduce the morbidity and mortality involved. During the study period, we tried to register all hospital-acquired infections even more systematically and to evaluate magnitude of DAIs per 100 hospital admission, magnitude of DAI cases per 1,000 bed days, incidence of infections per 1,000 device days, and median time for detection of DAIs.
This study diagnosed DAIs rate was 19.55% (113/578) which was higher than the rate of a previous INICC study (14.7%).  90% of them were associated with at least one of the invasive devices. From that we can conclude that invasive devices constitute significant risk factors for the development of DAIs. The difference (seen) from the result could be due to tt the fact that our study used the most serious patient population admitted in the ICU. Furthermore, the inclusion criteria of ICU stay was 48 h or longer in this study which resulted in higher infection incidence rates than those studies where these rates were calculated with considering all ICU or device days. 
Sex did not correlate much with the occurrence of DAIs  but in another study female patients were at lower risk for VAP but higher risk for CAUTI.  In our study population, most affected were among the age group of 40-60 years (37.4%) and then age group of 60-80 (29.2%), however HAIs peaked in the age group of >60 years, (32.7%) compared to the age group of 40-60 years (20.6%) and 20-40 years (18.9%) and <20 years it was only (13.7%). Hence, we can conclude that age is one of the significant risk factors for the development of HAIs in ITU. ,
More than 50% patients having different co-morbid illness were prone to developing DAIs [Table 1]. Malignancy (47%), CRD (42.8%), diabetes 35.2%, and COPD (30.5%) were more prone to acquiring DAIs. whereas CVA cases (15.6%) did not correlate much with DAIs probably because they were not having significant co-morbid illness. Hence, we can conclude that impaired immunity and chronic diseases were significant risk factors for the development of HAIs in ITU.
In this study, the device utilization ratio of VAP was lowest 0.305 whereas for CAUTI and CR-BSI was 0.836 and 0.737, respectively, whereas DAIs rate (incidence density) per 1,000 device days for VAP, CAUTI, and CR-BSI were 19.47, 4.25, and 3.99, respectively. Though the utilization of ventilator was lower than other devices but the incidence of infection was much higher, so ventilator was the most significant risk factor and caused infection earlier than other devices. This study also showed a lower use of MV (0.30 vs. 0.45) and higher use of CL (0.73 vs. 0.59) and UC (0.83 vs. 0.76) as compared to the device utilization reported by the US in the NHSN. 
Distribution of DAI was for VAP (43.36%), CAUTI (31.85%), and CR-BSI was (24.78%) was similar to other studies.  Our CR-BSI incidence density was 3.99/1,000 central venous catheter-days, which was lower than the INICC overall rate of 12.5 and slightly higher than the NHSN 2.9 rate. Our overall VAP rate by 1,000 MV-days was 19.47, lower than the 24.1 INICC rate but higher than the NHSN 3.1 rate. Our CAUTI rate (4.25/1000 UC days) was also lower than the INICC (8.9) and similar to NHSN (4.4) data [Table 2]. 
In this study, the median time of acquiring VAP, UTI, BSI were maximum within the range 9-14 days, 16-21 days, and 12-17 days, respectively, whereas the median time of acquiring the same infections in the absence of any devices were longer. In the study by van der Kooi et al., it was seen that patient who developed a DAI had significantly longer ICU stay also longer device use increased the risk of acquiring an infection especially CR-BSI and CAUTI.  Therefore, it is better to change these devices within the median time of infection or sample should be sent for microbiological test within this period both in cases of symptomatic and asymptomatic patients.
In the present study, the most commonly found organisms in ITU were Klebsiella spp. followed by Pseudomonus and Acinetobacter spp. each, S. aureus including MRSA and E. coli in decreasing order but in other studies Acinetobacter and Pseudomonas were the predominant pathogenic Gram-negative organisms of ITU.  Most frequent HAI was VAP (6.37%) and the most prevalent organisms in this group were Gram-negative organisms Klebsiella species (28.95%), Acinetobacter species (26.3%), Pseudomonas species (21%) and S. aureus (13%). CAUTI was the second most common DAIs and main causative organisms were Gram-negative bacteria of Enterobacteriacae group, of which E. coli (18%), Klebsiella (15%), Pseudomonas (15%), S. aureus, and candida spp. (12%) were common. Among CR-BSI, Gram-negative and Gram-positive organisms were equally found; these were Acinetobacter (18.5%) E. coli (14.8%), Klebsiella (11%), S. aureus (25.9%), CONS (10.7%), and Enterococcus (3.6%). This pattern of presenting organisms in different DAIs were nearly similar to other studies except the presence of Enterobacteriaceae group of organisms were high especially the Klebsiella spp. which was higher in the present study , but similar type of results we also found to another Indian study.  Hence, there is a need to be very cautious about these Enterobacteriaceae group of bacteria particularly the multidrug resistance Klebsiella, E. coli, Pseudomonas, Acinetobacter species.
The incidence of β lactamase producers in this study was found to be 68%, 60-90% of them showing multi-drug resistance against 2 nd and 3 rd generation cephalosporins, 90-100% against Piperacillin and 93-100% against aztreonam, 34-60% against cefepime, 54-77% against Amoxycillin-clavulanic acid. Multi-drug resistance to both ESBL and AmpC producers were found to be resistant to amikacin (32-44%), ciprofloxacin (67-89%), and cotrimoxazole (82-83%), respectively. Imipenem showing only 6% resistance in this study considered nowadays as the frontline antibiotic for the treatment of nosocomial infections caused by Enterobacteriaceae producing ESBL and AmpC beta-lactamases [Table 5]. Similar drug resistance pattern of antibiogram was reported in another Indian study and multidrug resistance is one of the leading cause of death found in this study. 
| Conclusion|| |
Intensive therapeutic unit-acquired infections are an independent risk factors for hospital mortality, morbidity, and increased hospital stay and cost. DU in critically ill patients is associated with increased risk of complications such as VAP, catheter-associated UTIs, and CR-BSI. One of the main strategies of preventing nosocomial infections in the ITU is an early change of invasive devices based on its median time of infection or avoiding unnecessary prolong use. We should not use this type of invasive devices longer than in its median time of infection but rather change it few days earlier while observing sterile precautions. A strict hand hygiene policy, staff education, and the implementation of maximal barrier precautions, especially the use of hand disinfection on catheter insertion and the handling of catheters and its regular follow-up might reduce the rate of DAIs.
Limitation of the Study
Over 2-year prospective collection of data from a single ITU is not a model representative of the whole hospital and also is not sufficient to give a reflection of the situation in the whole country.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]